Aptitude - Profit and Loss - Discussion

This solution is;

Because in the question profit or gain is being mentioned.

So G(Gain) = Sp(selling price) - Cp(cost price) ------> (1)
Or eq.(1) can also be written as;
Sp = (G+Cp) ------> (2).

And by what the question says we can make an equation as follows;
3G = 2Sp - Cp ------> (3)

Eq(2) in eq(3) and after solving eq(3).
We get G=Cp ------> (4).

Now in Gain% formula.
G% = (G*100)/Cp ------> (5).
Put the value of eq(4) in (5).
And G% equals to 100 (The answer).

The price of a commodity becomes tripled in 20 years. Find the average rate of increase.

Suppose c.p = x,
SP = 2x.
profit = 2x - x =x.
Profit % = (profit/ c.p )* 100 => (x / x) * 100.
Hence profit% = 100.

Thanks @Satish.

Let C.P=x.
S.P doubles then,S.P=2x,
Gain = S.P-C.P (2x-x),
Gain% = Gain/C.P * 100,
= 2x-x/x * 100,
= x/x * 100,
= 100%.

Lets the formula:

profit= sp-cp ------> (1)
Suppose cp=x sp=y.
In the question, sp doubles sp=2y.
Profit tripple means = profit =3(y-x)
In the equation 1 sub.
3(y-x)=2y-x,
Y=2x.
Profit= sp-cp= 2x-x=x,
Profit %=(cp/profit)*100,
= (x/x)*100
= 100.

Why we not take as 3z = 2y-x?

Simply, it is solved by;.

20 articles and 25 % we have taken 125 % so added 100.

20*100/125=16.

Let c.p. be x and s.p. be y.

We know that;
profit =s.p.-c.p.
=y-x------------> equation 1.

According to question;

Selling price is doubled then the profit triples so,

3(y-x)=2y-x -------------> (selling price is doubled and profit is tripled from equation 1)
or, 3y-3x=2y-x.
or, y=2x.

Now, keeping the value of y in equation 1 we get;
profit =2x-x.
=x,
Profit%= profit/c.p.
= x/x*100%,
=100%.

Let,

Sp = 30.
Profit = 10.

Now if sp becomes double the new sp would be 30*2= 60 and if profit triple then new profit would be = 10*3= 30.
So, new cp = 60-30=30.

So, profit percentage would be = new profit/new cp *100.
= 30/30*100 =100%.